Heat generator

ABSTRACT

The purpose of the present invention is to provide a heat generator that comprises an adhesive layer containing a volatile component and in which the volatile component is maintained in a stable state during storage, the volatile component is prevented from adhering to a heat-generating section, and it is possible to achieve an excellent warming effect during use. This heat generator comprises: a heat-generating section, an accommodation body that accommodates the heat-generating section and comprises an attachment surface to which an attachment body is attached, an adhesive layer provided to the attachment surface side of the accommodation body, and a release sheet provided to the attachment surface side of the adhesive layer. As a result of including a volatile component in the adhesive layer and providing a metal foil membrane to the release sheet, it is possible to maintain the volatile component in a stable state within the adhesive layer during storage. It is thereby possible to prevent the adhesion of the volatile component to the heat-generating section during storage and to achieve an excellent warming effect during use.

TECHNICAL FIELD

The present invention relates to a heat generator that is used by beingattached to an adherend such as a skin or clothing and that contains avolatile component. More specifically, the present invention relates toa heat generator including a pressure-sensitive adhesive layercontaining a volatile component, where the volatile component is stablymaintained in the pressure-sensitive adhesive layer during storage, sothat the functions provided by the volatile component and the warmingfunctions are excellent during use.

BACKGROUND ART

A heat generator using a heat-generating composition that generates heatby being brought into contact with air is widely used not only as awarming tool for prevention of coldness or the like but also as a curingtool or the like for promotion of good blood circulation, alleviation ofpain, or the like. Also, in recent years, by receiving enhanced demandfor improvement in the functionality of heat generators, development ofa heat generator imparted with various functionalities is put to trial.

Conventionally, there is developed a heat generator that can impartscent or sensation of coolness by incorporation of a volatile component.For example, Patent Document 1 reports a heat generator in which aheat-generating section including an oxidizable metal, a reactionpromoter, an electrolyte, and water is accommodated in an accommodationbody, where the heat-generating section contains a cold sensationimparting agent that imparts coolness to the skin and a solvent thatdissolves the cold sensation imparting agent. However, a heat generatorin which the cold sensation imparting agent is directly blended in theheat-generating section such as disclosed in Patent Document 1 hasdisadvantages such that the cold sensation imparting agent is adhered toan oxidation promoter (activated carbon or the like) that is containedin the heat-generating section, whereby the sensation of coolness givenby the cold sensation imparting agent may decrease, and further, thewarming function exhibited by the heat-generating section may decreaseor become non-uniform.

In the meantime, there is also a report on a heat generator in which avolatile component is incorporated into a constituent member other thana heat-generating section. For example, Patent Document 2 discloses thata heat generator provided with a heat-generating section containing anoxidizable metal and activated carbon, and a bag body at least a part ofwhich has gas permeability and which accommodates the heat-generatingsection, where a scent-imparting sheet in which a perfume compositioncontaining a monoterpenoid having a cyclic ether structure and amonoterpenoid having a cyclic ketone structure is incorporated at aspecific ratio is disposed between the heat-generating body and the bagbody, provides good rise in the scent during use, and degeneration ofscent during storage hardly occurs. Also, Patent Document 3 disclosesthat a heat generator having a heat-generating section containing anoxidizable metal and activated carbon, and a bag body that isconstituted with a sheet at least a part of which has gas permeabilityand at least a part of which has a weight of 20 to 90 g/m² and thataccommodates the heat-generating section, where a scent-imparting sheet,in which a perfume composition containing 0.2 to 0.7 mass % ofdamascenone is incorporated, is disposed between the heat-generatingbody and the bag body, exhibits a good scent, which is of the timeimmediately after production, during use as well. However, since a heatgenerator is stored generally in a state of being accommodated in atight sealing bag, even the cases of incorporating a volatile componentinto a constituent member other than a heat-generating section such asdisclosed in Patent Documents 2 and 3 have disadvantages such that, bymigration and adsorption of the volatile component into theheat-generating section during storage, the function of the volatilecomponent itself may decrease, and further, the warming functionprovided by the heat-generating section may decrease or becomenon-uniform.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Laid-open Publication No. 2014-205072

Patent Document 2: Japanese Patent Laid-open Publication No. 2011-160885

Patent Document 3: Japanese Patent Laid-open Publication No. 2013-42963

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In a heat generator in which a volatile component is incorporated into aconstituent member other than a heat-generating section such asdisclosed in Patent Documents 2 and 3, migration of the volatilecomponent into the heat-generating section during storage seems to becaused by permeation of the volatile component into the heat-generatingsection via a gas-permeable site of the bag body that accommodates theheat-generating section through volatilization of the volatile componentin the tight sealing bag.

Also, a heat generator provided with a pressure-sensitive adhesive layeris typically circulated and stored by being accommodated in a tightsealing bag in a state in which a release sheet made of a resin film isin close adhesion to the pressure-sensitive adhesive layer. When avolatile component is incorporated in the pressure-sensitive adhesivelayer in such a heat generator provided with the pressure-sensitiveadhesive layer, the volatile component is volatilized and scattered intothe tight sealing bag via the release sheet (resin film) in the tightsealing bag, so that penetration of the volatile component into theheat-generating section cannot be prevented. Also, in a general heatgenerator, an accommodation body that accommodates the heat-generatingsection is formed in such a manner that two sheets of packagingmaterials are bonded at peripheral parts, so that the accommodation bodyhas a peripheral bonding section and an accommodation section (spacepart), and step difference is generated at the boundary between theperipheral bonding section and the accommodation section. This raises adisadvantage in that, even when the release sheet (resin film) isbrought into close adhesion to the pressure-sensitive adhesive layer,the release sheet cannot follow the step difference, and a gap isgenerated in the peripheral bonding section region because the releasesheet cannot be in close adhesion to the pressure-sensitive adhesivelayer, so that the volatile component contained in thepressure-sensitive adhesive layer is volatilized and scattered from thegap into the tight sealing bag, and penetration of the volatilecomponent into the heat-generating section cannot be prevented.

Accordingly, an object of the present invention is to provide a heatgenerator that includes a pressure-sensitive adhesive layer containing avolatile component and in which the volatile component is stablymaintained during storage, the volatile component is prevented fromadhering to the heat-generating section, and it is possible to achievean excellent warming effect during use.

Means for Solving the Problems

The present inventor has made eager studies in order to solve theaforementioned problems and has found out that a heat generator having aheat-generating section, an accommodation body for accommodating theheat-generating section, the accommodation body having an attachmentsurface that is attached to the adherend, a pressure-sensitive adhesivelayer provided to an attachment surface side of the accommodation body,and a release sheet provided to the attachment surface side of thepressure-sensitive adhesive layer, in which a volatile component isincorporated into the pressure-sensitive adhesive layer and in which therelease sheet includes a metal foil membrane, makes it possible tostably maintain the volatile component within the pressure-sensitiveadhesive layer during storage and, as a result, makes it possible toprevent the volatile component from adhering to the heat-generatingsection during storage and to achieve an excellent warming effect duringuse. The present invention has been completed by repetitively makingfurther studies based on such knowledge.

That is, the present invention provides inventions having modes listedin the following.

Item 1: A heat generator that is used by being attached to an adherend,the heat generator comprising:

a heat-generating section for generating heat that is transmitted to theadherend;

an accommodation body for accommodating the heat-generating section, theaccommodation body having an attachment surface that is attached to theadherend:

a pressure-sensitive adhesive layer provided to an attachment surfaceside of the accommodation body; and

a release sheet provided to an attachment surface side of thepressure-sensitive adhesive layer and being releasable from thepressure-sensitive adhesive layer, wherein

the accommodation body is composed of a first packaging materialdisposed on an attachment surface side and a second packaging materialdisposed on a surface opposite to the attachment surface,

the accommodation body includes a peripheral bonding section whereperipheral parts of the first packaging material and the secondpackaging material are bonded, and an accommodation section that forms aspace for accommodating the heat-generating section,

the pressure-sensitive adhesive layer is provided at least in a regionwhere the peripheral bonding section of the first packaging material isformed, and

the release sheet includes a metal foil membrane.

Item 2: The heat generator according to Item 1, wherein the releasesheet is in close adhesion to the pressure-sensitive adhesive layer byfollowing a step difference that is generated at a boundary between theperipheral bonding section and the space part of the accommodation body.

Item 3: The heat generator according to Item 1 or 2, wherein

the release sheet has a concave-convex shape in a region where theperipheral bonding section of the first packaging material is formed,and

the pressure-sensitive adhesive layer has a concave-convex shape thatfollows the concave-convex shape of the release sheet.

Item 4: The heat generator according to Item 3, wherein theconcave-convex shapes of the release sheet and the pressure-sensitiveadhesive layer are formed by an embossing treatment.

Item 5: The heat generator according to any one of Items 1 to 4, whereinthe first packaging material has an oxygen permeability of 1.5cc/m²·day·atm or less.

Item 6: The heat generator according to any one of Items 1 to 5, whereinthe metal foil membrane is an aluminum foil membrane or a stainlesssteel foil membrane.

Item 7: The heat generator according to any one of Items 1 to 6, whereinthe volatile component is at least one kind selected from the groupconsisting of menthol, camphor, thymol, spilanthol, mint oil, peppermintoil, methyl salicylate, capsaicin, vanillyl nonylic acid amide, sage,caffeine, tocopherol nicotinate, benzyl nicotinate, vanillyl butylether, vanillyl ethyl ether, gingerol, vanillyl propyl ether, vanillylpentyl ether, vanillyl hexyl ether, vanillyl butyl ether acetate, hotpepper extract, and ginger extract.

Item 8: The heat generator according to any one of Items 1 to 7, whereinthe release sheet does not have a penetrating section that penetrates ina thickness direction.

Advantages of the Invention

According to the heat generator of the present invention, it is possibleto stably maintain the volatile component within the pressure-sensitiveadhesive layer and to prevent the volatile component from adhering tothe heat-generating section during storage, so that the functions andeffects provided by the volatile component can be effectively enjoyedduring use. Also, in the heat generator of the present invention, theheat generation characteristics of the heat-generating section arestably maintained by preventing the volatile component from adhering tothe heat-generating section during storage, so that the heat generationtemperature can be prevented from decreasing or becoming non-uniformduring use, and an excellent warming effect can also be achieved duringuse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a cross-sectional structure of apreferable embodiment of the heat generator of the present invention.

FIG. 2 is a schematic view of a cross-sectional structure of apreferable embodiment of the heat generator of the present invention.

FIG. 3 is an enlarged schematic view of the region E shown in FIG. 1.

FIG. 4 is a graph showing results of evaluating the heat generationcharacteristics after the heat generators of Example 1 and ComparativeExample 1 (each with 10 pieces) were stored at 50° C. for two months.

FIG. 5 is a graph showing results of evaluating over time the sensationof hotness and the sensation of coldness that were perceived after theheat generators of Example 4 and Comparative Example 3 (each with 10pieces) were stored at 50° C. for two months.

EMBODIMENTS OF THE INVENTION

The heat generator of the present invention is a heat generator that isused by being attached to an adherend and includes a heat-generatingsection 1 for generating heat that is transmitted to the adherend, anaccommodation body 2 for accommodating the heat-generating section 1,the accommodation body 2 having an attachment surface that is attachedto the adherend, a pressure-sensitive adhesive layer 3 provided to anattachment surface side of the accommodation body 2, and a release sheet4 provided to an attachment surface side of the pressure-sensitiveadhesive layer 3 and being releasable from the pressure-sensitiveadhesive layer 3, characterized in that the accommodation body 2 iscomposed of a first packaging material 21 disposed on an attachmentsurface side and a second packaging material 23 disposed on a surfaceopposite to the attachment surface; the accommodation body 2 includes aperipheral bonding section 24 where peripheral parts of the firstpackaging material 21 and the second packaging material 23 are bonded,and an accommodation section 22 that forms a space for accommodating theheat-generating section; the pressure-sensitive adhesive layer 3 isprovided at least in a region where the peripheral bonding section 24 ofthe first packaging material 21 is formed; and the release sheet 4includes a metal foil membrane 41. Hereafter, the heat generator of thepresent invention will be described in detail.

<Heat-Generating Section 1>

The heat generator of the present invention includes a heat-generatingsection 1 for generating heat that is transmitted to an adherend. Theheat-generating section 1 performs a function of generating heat andimparting a sensation of hotness.

The heat generation mechanism of the heat-generating section 1 is notparticularly limited as long as the heat-generating section 1 cangenerate heat and can transmit the heat to the adherend. Examples of theheat-generating section include a heat-generating composition thatgenerates heat by being brought into contact with oxygen; anenergization heat generating body that generates heat by beingenergized; a heat generating body that generates heat by receivingradiation of a microwave; and a heat generating body that generates heatby using a liquid, semisolid, or solid heat-storing material. Amongthese, a heat-generating composition that generates heat by beingbrought into contact with oxygen is strongly liable to invite decreaseor weakening of the warming function by mingling of a volatile componentor to invite non-uniform heat generation characteristics that areexhibited; however, in the heat generator of the present invention, suchpermeation of the volatile component into the heat-generating section 1is effectively prevented. In view of such effects of the presentinvention, a heat-generating composition that generates heat by beingbrought into contact with oxygen is suitable as the heat-generatingsection 1. Also, a heat-generating composition that generates heat bybeing brought into contact with oxygen can be disposed of after beingused and is hence suitable in view of safety, heat-generationefficiency, convenience, and the like as well.

The components of the heat-generating composition that generates heat bybeing brought into contact with oxygen are not particularly limited andmay be those that are conventionally used in a disposable pocket warmeror the like. One suitable example of the heat-generating compositionthat generates heat by being brought into contact with oxygen may be acomposition containing an oxidizable metal, an oxidation promoter, andwater.

In the heat-generating composition, the oxidizable metal performs afunction of being oxidized by being brought into contact with oxygen tobecome a heat generation source with oxidation heat. The type of theoxidizable metal is not particularly limited as long as heat can begenerated by oxidation. Examples of the oxidizable metal include metalssuch as iron (reduced iron, cast iron, atomized iron, electrolyticiron), aluminum, zinc, manganese, magnesium, and calcium. Theseoxidizable metals may be used either alone as one kind or as acombination of two or more kinds.

Also, the shape of the oxidizable metal is not particularly limited;however, in view of the heat generation efficiency, the shape of theoxidizable metal is preferably powdery, granular, or fibrous, and moreparticularly is powdery.

Among these oxidizable metals, iron powder is preferable in view ofsafety, facility in handling, and the like.

When the oxidizable metal is powdery, the particle size thereof is notparticularly limited and may be, for example, 0.01 to 1000 μm,preferably 0.1 to 500 μm, more preferably 0.5 to 300 μm, and still morepreferably 30 to 250 μm. Here, the particle size of the powderyoxidizable metal is a value that is determined in accordance with “Drysieving test” defined in JIS8815-1994 “Test sieving—Generalrequirements”.

The content of the oxidizable metal in the heat-generating compositionis suitably set in accordance with the heat generation characteristicsthat are to be imparted, and may be, for example, 20 to 80 wt %,preferably 25 to 70 wt %, and more preferably 30 to 60 wt %.

Also, in the heat-generating composition, the oxidation promoterperforms a function of retaining oxygen and supplying oxygen to theoxidizable metal. The type of the oxidation promoter is not particularlylimited as long as the oxidation promoter can retain oxygen and supplyoxygen to the oxidizable metal. Examples of the oxidation promoterinclude carbon materials such as activated carbon, carbon black,acetylene black, bamboo carbon, charcoal, coffee residue carbon,graphite, coal, coconut shell carbon, bituminous coal, peat, andlignite. These oxidation promoters may be used either alone as one kindor as a combination of two or more kinds.

Among these oxidation promoters, activated carbon, carbon black, bamboocarbon, charcoal, and coffee residue carbon are preferable, andactivated carbon is more preferable.

Also, the shape of the oxidation promoter is not particularly limited;however, in view of the heat generation efficiency, the shape of theoxidation promoter is preferably powdery, granular, or fibrous, and moreparticularly is powdery.

When the oxidation promoter is powdery, the particle size thereof is notparticularly limited and may be, for example, 0.001 to 1000 μm,preferably 0.005 to 500 μm, and more preferably 0.01 to 200 μm. Here,the particle size of the powdery oxidation promoter is a value that isdetermined in accordance with “Dry sieving test” defined in JIS8815-1994“Test sieving—General requirements”.

The content of the oxidation promoter in the heat-generating compositionis suitably set in accordance with the heat generation characteristicsthat are to be imparted and the like, and may be, for example, 1 to 30wt %, preferably 3 to 25 wt %, and more preferably 5 to 23 wt %.

Also, in the heat-generating composition, the ratio of the oxidationpromoter to the oxidizable metal is suitably set in accordance with theheat generation characteristics that are to be imparted, and may be, forexample, such that the oxidation promoter is contained at 2 to 60 partsby weight, preferably 5 to 50 parts by weight, and more preferably 10 to40 parts by weight, relative to 100 parts by weight of the oxidizablemetal.

Further, in the heat-generating composition, water performs a functionof oxidizing the oxidizable metal together with oxygen. Water to be usedmay be any of distilled water, ion exchange water, pure water, ultrapurewater, tap water, industrial water, and the like.

The content of water in the heat-generating composition is suitably setin accordance with the heat generation characteristics that are to beimparted, and may be, for example, 5 to 50 wt %, preferably 10 to 40 wt%, and more preferably 15 to 35 wt %.

In addition to the aforementioned components, the heat-generatingcomposition may contain water-soluble salts in accordance with theneeds. When water-soluble salts are contained, oxidation of theoxidizable metal can be promoted.

The type of the water-soluble salt is not particularly limited, andexamples thereof include sulfates, hydrogencarbonates, chlorides, andhydroxides of alkali metals (sodium, potassium, and others), alkalineearth metals (calcium, magnesium, and others), and heavy metals (iron,copper, aluminum, zinc, nickel, silver, barium, and others). Among thesewater-soluble salts, chlorides such as sodium chloride, potassiumchloride, calcium chloride, magnesium chloride, and iron chloride(ferrous chloride, ferric chloride) are preferable, and sodium chlorideis more preferable, in view of electric conductivity, chemicalstability, and the like. These water-soluble salts may be used eitheralone as one kind or as a combination of two or more kinds.

When a water-soluble salt is blended into the heat-generatingcomposition, the content of the water-soluble salt is suitably set inaccordance with the heat generation characteristics that are to beimparted, and may be, for example, 0.1 to 10 wt %, preferably 0.5 to 7wt %, and more preferably 1 to 5 wt %.

Further, the heat-generating composition may contain a water retentionagent in accordance with the needs. The water retention agent performs afunction of retaining water and supplying water to the oxidationreaction field.

The type of the water retention agent is not particularly limited, andexamples thereof include inorganic porous materials such as vermiculite(expanded vermiculite), pearlite, calcium silicate, magnesium silicate,kaolin, talc, smectite, mica, bentonite, calcium carbonate, silica gel,alumina, zeolite, silicon dioxide, and diatomaceous earth; organicmaterials such as pulp, wood powder (sawdust), cotton, starches, andcelluloses; and water-absorbing resins such as polyacrylate resin,polysulfonate resin, maleic anhydride resin, polyacrylamide resin,polyvinyl alcohol resin, polyethylene oxide resin, polyaspartate resin,polyglutamate resin, and polyalginate resin. These water retentionagents may be used either alone as one kind or as a combination of twoor more kinds.

Among these water retention agents, vermiculite, polyacrylate resin,wood powder, and pulp are preferable; and vermiculite and polyacrylateresin are more preferable. Also, when an inorganic porous material isused as the water retention agent, an air flow passageway can also beensured in the heat-generating composition.

The particle size of the water retention agent is not particularlylimited and may be, for example, 0.1 to 3000 μm, preferably 0.5 to 1000pun, and more preferably 1 to 1000 μm. Here, the particle size of thewater retention agent is a value that is determined in accordance with“Dry sieving test” defined in JIS8815-1994 “Test sieving—Generalrequirements”.

When a water retention agent is blended into the heat-generatingcomposition, the content of the water retention agent is suitably set inaccordance with the heat generation characteristics that are to beimparted, and may be, for example, 1 to 20 wt %, preferably 3 to 15 wt%, and more preferably 5 to 10 wt %.

The heat-generating composition may further contain other additives suchas a metal ion blocking agent, a perfume, a thickening agent, anexcipient, a surfactant, and a hydrogen generation suppresser inaccordance with the needs.

The heat-generating composition can be prepared by blendingpredetermined amounts of the aforementioned components. The preparationof the heat-generating composition may be carried out in the presence ofoxygen; however, the heat-generating composition is preferably preparedunder reduced pressure or in an inert gas atmosphere.

The heat-generating section 1 is set so that heat is generated toachieve a suitable temperature when the heat generator of the presentinvention is attached to the adherend. The maximum attained temperatureof the heat generator of the present invention may be suitably set inaccordance with the type and site of the adherend serving as an objectof application, the sensation of hotness and warming function to beimparted, and the like, and may be, for example, about 32 to 85° C.,preferably about 34 to 70° C. The maximum attained temperature is avalue determined in accordance with the method defined in JISS4100:2007.

<Accommodation Body 2>

The heat generator of the present invention is provided with anaccommodation body 2 that accommodates the heat-generating section 1.The accommodation body 2 has an accommodation section 22 foraccommodating the heat-generating section 1.

In the accommodation body 2, the first packaging material 21 disposed onthe attachment surface side may be formed of a resin layer, a fiberlayer, or the like; however, the first packaging material 21 preferablyincludes a gas barrier layer 211 having a gas barrier function. Byproviding the gas barrier layer 211 in the first packaging material 21,it is possible to prevent the volatile component contained in thepressure-sensitive adhesive layer 3 from directly migrating into theinside of the accommodation section 22, so that the volatile componentcan be maintained furthermore stably within the pressure-sensitiveadhesive layer 3 during storage. Also, by providing the gas barrierlayer 211 in the first packaging material 21, the oxygen permeabilityand the water vapor permeability that are described later can besuitably satisfied. In the present invention, a gas barrier layer refersto a layer that is made of a material capable of preventing permeationof the volatile components.

The material constituting the gas barrier layer 211 is not particularlylimited and may be, for example, a metal foil membrane, a vapordeposition film, a thermoplastic resin layer capable of shutting off thepermeation of volatile components (which may hereafter be denoted as“barrier resin layer”), or the like.

The metal foil membrane used as the gas barrier layer 211 may be, forexample, an aluminum foil membrane, a stainless steel foil membrane, orthe like. Among these metal foil membranes, an aluminum foil membrane ispreferable.

The thickness of the metal foil membrane is not particularly limited andmay be, for example, 5 to 50 μm, preferably 5 to 15 μm.

The metal foil membrane can be laminated onto a material that forms anadjacent layer by a known lamination method such as dry lamination,extrusion lamination, or heat lamination.

The material that constitutes a vapor deposition film used as the gasbarrier layer 211 is not particularly limited as long as the materialcan shut off the permeation of volatile components, and examples of thematerial include metals such as aluminum, chromium, zinc, gold, silver,platinum, and nickel; inorganic oxides such as silica, titanium oxide,aluminum oxide, and zirconium oxide; and inorganic fluorides such asmagnesium fluoride.

The thickness of the vapor deposition film is not particularly limitedas long as the thickness is within a range such that the permeation ofvolatile components can be prevented, and the thickness may be, forexample, 50 to 5000 Å, preferably 100 to 1000 Å.

The vapor deposition film can be formed by vapor deposition of theaforementioned material onto a material that forms an adjacent layer bya known vapor deposition method such as the physical vapor depositionmethod or the chemical vapor deposition method.

The resin constituting the barrier resin layer used as the gas barrierlayer 211 is not particularly limited as long as the resin can shut offthe permeation of volatile components, and the resin may be, forexample, polyvinylidene chloride.

The barrier resin layer can be formed by forming a coating film on amaterial that forms an adjacent layer by a known resin coating method.

The thickness of the barrier resin layer is not particularly limited aslong as the thickness is within a range such that the permeation ofvolatile components can be prevented, and the thickness may be, forexample, 0.5 to 30 μm, preferably 0.8 to 10 μm, and more preferably 1 to2 μm.

In the first packaging material 21, the gas barrier layer 211 may be asingle layer made of one constituent material or a multiple layer madeof two or more of the same or different materials. Among the materialsconstituting the gas barrier layer 211, the first gas barrier layer 211is preferably made of a metal foil membrane and still more preferably analuminum foil membrane, in view of more effectively preventing directmigration of the volatile component into the inside of the accommodationsection 22 and stably maintaining the volatile component within thepressure-sensitive adhesive layer 3 during storage. Also, when a metalfoil membrane or a vapor deposition film is used as the first gasbarrier layer 211, the heat conductivity from the heat-generatingsection 1 to the adherend is improved, so that hotness can be perceivedearly from the start of use, and further the sensation of hotness can beimproved by radiation heat that is emitted from the metal foil membraneor vapor deposition film.

In the first packaging material 21, the surface of the accommodationsection 22 side preferably contains a welded resin layer 212 formed of athermoplastic resin excellent in heat weldability. By providing thewelded resin layer 212 in such a manner, peripheral parts of the firstpackaging material 21 and the second packaging material 23 can be easilybonded, and the accommodation body 2 can be formed in a convenient andsimple manner. The thermoplastic resin constituting the welded resinlayer 212 may be specifically, for example, a polyolefin such aspolyethylene or polypropylene.

The thickness of the welded resin layer 212 is not particularly limitedand may be, for example, 1 to 200 μm, preferably 30 to 100 μm.

Further, in the first packaging material 21, it is preferable that afiber substrate 213 is provided onto the surface that is in surfacecontact with the pressure-sensitive adhesive layer 3. By providing thefiber substrate 213 in this manner, the temperature of the attachmentsurface of the heat generator of the present invention onto the adherendcan be adjusted, and also the sensation of use at the time of attachingthe heat generator of the present invention onto a skin can be improved.

The fiber substrate 213 may be specifically, for example, a nonwovencloth or woven cloth. In view of the sensation of use and the like, thefiber substrate 213 is preferably made of a nonwoven cloth. The materialof the fiber substrate 213 is not particularly limited, and examplesthereof include synthetic fibers such as polyethylene terephthalate,polybutylene terephthalate, nylon, polypropylene, polyethylene, vinylon,rayon, acryl, acetate, and polyvinyl chloride; natural fibers such ascotton, linen, silk, and paper; and mixed fibers of these. Among thesematerials, the fiber substrate 213 is preferably made of polyethyleneterephthalate, nylon, or polypropylene, more preferably polyethyleneterephthalate or nylon, in view of enhancing the sensation of use.

The weight per unit area of the fiber substrate 213 may be suitably setin accordance with the layer configuration of the first packagingmaterial 21 and the like, and may be, for example, 10 to 100 g/m²,preferably 15 to 70 g/m², and more preferably 20 to 50 g/m².

The fiber substrate 213 can be laminated onto a material that forms anadjacent layer by a known lamination method such as dry lamination,extrusion lamination, or heat lamination.

Further, besides the aforementioned layers, the first packaging material21 may include a first resin layer 214 made of a resin layer other thanthe barrier resin layer and the welded resin layer 212 in accordancewith the needs. In particular, the first resin layer is used as asubstrate layer for supporting the vapor deposition film or the barrierresin layer when the vapor deposition film or the barrier resin layer isused as the gas barrier layer 211.

When the first resin layer 214 is provided in the first packagingmaterial 21, the first resin layer 214 may be disposed, for example,between the welded resin layer 212 and the gas barrier layer 211 and/orbetween the gas barrier layer 211 and the fiber substrate 213.

The resin constituting the first resin layer 214 is not particularlylimited and may be, for example, a thermoplastic resin such aspolyethylene terephthalate, polyacrylonitrile, or ethylene-vinyl alcoholcopolymer. Among these resins, polyethylene terephthalate is apreferable example.

The thickness of the first resin layer 214 is not particularly limitedand may be, for example, 1 to 100 μm, preferably 3 to 50 μm.

The oxygen permeability of the first packaging material 21 is notparticularly limited; however, in view of effectively preventing directmigration of the volatile component into the inside of the accommodationsection 22 and allowing the volatile component to be furthermore stablymaintained within the pressure-sensitive adhesive layer 3 duringstorage, the oxygen permeability of the first packaging material 21 ispreferably 1.5 cc/m²·day·atm or less, more preferably 0 to 1cc/m²·day·atm, still more preferably 0 to 0.5 cc/m²·day·atm, andparticularly preferably 0 to 0.1 cc/m²·day·atm. In the presentspecification, the “oxygen permeability” is a value determined underconditions with a temperature of 20° C. and a humidity of 90% RH inaccordance with the differential pressure method defined in JIS K7126-1:2006.

Also, the water vapor permeability of the first packaging material 21 isnot particularly limited; however, in view of effectively preventingdirect migration of the volatile component into the inside of theaccommodation section 22 and allowing the volatile component to befurthermore stably maintained within the pressure-sensitive adhesivelayer 3 during storage, the water vapor permeability of the firstpackaging material 21 is preferably 1.5 g/m²-day or less, morepreferably 0 to 1 g/m²·day, still more preferably 0 to 0.5 g/m²·day, andparticularly preferably 0 to 0.1 g/m²·day. In the present specification,the “water vapor permeability” is a value determined under conditionswith a temperature of 40° C. and a humidity of 90% RRH in accordancewith the cup method defined in JIS Z0208:1976.

A preferable mode of the layer structure of the first packaging material21 may be, for example, a lamination structure in which the welded resinlayer 212, the gas barrier layer 211 made of a metal foil membrane, andthe fiber substrate 213 are laminated in this order; or a laminationstructure in which the welded resin layer 212, the first resin layer214, the gas barrier layer 211 made of a vapor deposition film, and thefiber substrate 213 are laminated in this order, in a direction from theinside of the accommodation section 22 towards the pressure-sensitiveadhesive layer 3 side.

The second packaging material 23 that is disposed opposite to theattachment surface side in the accommodation body 2 can be formed of amaterial similar to that of a packaging material of the accommodationbody 2, the packaging material being provided on the non-attachmentsurfaced side, in a conventional heat generator. When a heat-generatingcomposition that generates heat by being brought into contact withoxygen is used as the heat-generating section 1, it is necessary thatthe second packaging material 23 is provided with gas permeability.However, when a material other than the heat-generating composition isused as the heat-generating section 1, the second packaging material 23may be either gas-permeable or non-gas-permeable.

The second packaging material 23 having gas permeability can be formed,for example, with a gas-permeable resin layer 231, a fiber substrate232, and the like.

The constituent resin of the gas-permeable resin layer 231 used forforming the second packaging material 23 having gas permeability is notparticularly limited, and may be, for example, a thermoplastic resin.Specific examples of the thermoplastic resin include polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polyethyleneterephthalate, polyacrylonitrile, ethylene-vinyl alcohol copolymer,polyamide, polyurethane, polystyrene, polyvinyl alcohol, polyvinylchloride, polyvinylidene chloride, and polycarbonate. Among thesethermoplastic resins, polyethylene, polypropylene, and ethylene-vinylacetate copolymer are preferable examples.

Also, the gas-permeable resin layer 231 may be specifically a resin filmin which pores for ensuring gas permeability are provided. The shape,size, and number of the pores provided in the resin film may be suitablyset in accordance with the gas permeability that is to be provided inthe accommodation body 2.

The thickness of the gas-permeable resin layer 231 may be suitably setin accordance with the layer configuration of the second packagingmaterial and the like, and may be, for example, 15 to 150 μm, preferably30 to 100 μm, and more preferably 50 to 80 μm.

The fiber substrate 232 used in the second packaging material 23 may bespecifically, for example, a nonwoven cloth or woven cloth. In view ofthe sensation of use and the like, the fiber substrate 232 is preferablymade of a nonwoven cloth. The material of the fiber substrate 232 is notparticularly limited, and examples thereof include synthetic fibers suchas polyethylene terephthalate, polybutylene terephthalate, nylon,polypropylene, polyethylene, vinylon, rayon, acryl, acetate, andpolyvinyl chloride; natural fibers such as cotton, linen, silk, andpaper; and mixed fibers of these. Among these materials, the fibersubstrate 232 is preferably made of polyethylene terephthalate, nylon,or polypropylene, more preferably polyethylene terephthalate or nylon,in view of enhancing the sensation of use.

The weight per unit area of the fiber substrate 232 may be suitably setin accordance with the layer configuration of the second packagingmaterial 23 and the like, and may be, for example, 1 to 100 g/m²,preferably 5 to 70 g/m², and more preferably 10 to 50 g/m².

The layer structure of the second packaging material 23 having gaspermeability may be specifically, for example, a single-layer structuremade of the gas-permeable resin layer 231 or the fiber substrate 232; ora multiple-layer structure in which two or more of the same or differentmaterials selected from the gas-permeable resin layer 231 and the fibersubstrate 232 are combined. In view of improving the sensation of use,preventing leakage of the heat-generating composition, and the like, thelayer structure of the second packaging material 23 is preferably asingle-layer structure made of the gas-permeable resin layer 231 or alamination structure in which the gas-permeable resin layer 231 and thefiber substrate 232 are laminated in this order in a direction from theinside of the accommodation body 2 towards the outside.

Lamination of the gas-permeable resin layer 231 and the fiber substrate232 can be carried out by a known lamination method such as drylamination, extrusion lamination, or heat lamination.

The accommodation body 2 is formed by bonding the first packagingmaterial 21 and the second packaging material 23 at sites surroundingthe region that is to become the accommodation section 22 foraccommodating the heat-generating section 1. In other words, in theaccommodation body 2, there are formed the accommodation section 22 thatforms a space for accommodating the heat-generating section and theperipheral bonding section 24 where the peripheral parts of the firstpackaging material 21 and the second packaging material 23 are bonded.Also, when the peripheral parts of the first packaging material 21 andthe second packaging material 23 are bonded in this manner, a stepdifference 2 a (height difference) is formed at a boundary between theperipheral bonding section 24 and the accommodation section 22 (SeeFIGS. 1 and 2).

A method for bonding the first packaging material 21 and the secondpackaging material 23 is not particularly limited. For example, a methodof heat welding (heat sealing) by using the welded resin layer 212included in the first packaging material 21, a method of bonding withuse of an adhesive agent, or the like may be adopted.

When a heat-generating composition that generates heat by being broughtinto contact with oxygen is used as the heat-generating section 1, theamount of the heat-generating composition accommodated in theaccommodation section 22 of the accommodation body 2 may be suitably setin accordance with the type and site of the adherend that is to beattached, the heat generation characteristics of the heat-generatingcomposition, and the like, and may be, for example, such that the amountof the heat-generating composition is about 0.01 to 1.5 g, preferablyabout 0.05 to 1 g, and more preferably about 0.1 to 0.8 g. per 1 cm² ofthe area of the first packaging material 21 in the region that forms theaccommodation section 22.

In the accommodation body 2 used in the present invention, the number ofthe accommodation sections 22 that accommodate the heat-generatingsection 1 is not particularly limited and may be either one or plural.The number of the accommodation sections 22 is suitably set inaccordance with the type and site of the adherend that is to be attachedor the like. Also, the size and shape of the accommodation section 22 isnot particularly limited and is suitably set in accordance with theshape of the adherend that is to be attached or the like.

<Pressure-Sensitive Adhesive Layer 3>

In the heat generator of the present invention, a pressure-sensitiveadhesive layer 3 containing a volatile component is provided to theattachment surface in the accommodation body 2. By providing such apressure-sensitive adhesive layer 3, it is possible to attach the heatgenerator to a predetermined site of the adherend in a convenient andsimple manner without separately using a fixing tool for fixing the heatgenerator onto the adherend. Also, since the volatile component iscontained in the pressure-sensitive adhesive layer 3, it is possible toexhibit a function based on the volatile component together with thewarming function during use.

The type of the volatile component contained in the pressure-sensitiveadhesive layer 3 is not particularly limited, and may be, for example, acomponent having volatility and being capable of imparting fragrance,sensation of coolness, sensation of hotness, and the like. Specificexamples of such a volatile component include cold sensation impartingagents such as menthol, camphor, thymol, spilanthol, mint oil,peppermint oil, and methyl salicylate; hot sensation imparting agentssuch as capsaicin, vanillyl nonylic acid amide, sage, caffeine,tocopherol nicotinate, benzyl nicotinate, vanillyl butyl ether, vanillylethyl ether, gingerol, vanillyl propyl ether, vanillyl pentyl ether,vanillyl hexyl ether, vanillyl butyl ether acetate, hot pepper extract(extract of hot pepper with water or water-containing ethanol (ethanolcontent being about 30 to 95 wt %)), and ginger extract (extract ofginger with water or water-containing ethanol (ethanol content beingabout 30 to 95 wt %)); and other perfume components. These volatilecomponents may be used either alone as one kind or in combination of twoor more kinds. In particular, when a cold sensation imparting agent anda hot sensation imparting agent are used in combination as the volatilecomponent, the sensation of coldness can be imparted while increasingthe sensation of hotness that is imparted, so that the sensation of useand the blood flow rate can be improved. Among these volatilecomponents, menthol, camphor, and ginger extract are preferableexamples.

The content of the volatile component in the pressure-sensitive adhesivelayer 3 is not particularly limited and may be, for example, 0.0001 to20 wt %, preferably 0.005 to 15 wt/o, and more preferably 0.001 to 10 wt%. Here, when the volatile component is an extract, the content refersto a value as converted in terms of dry weight.

Further, in addition to the volatile component, the pressure-sensitiveadhesive layer 3 contains a pressure-sensitive adhesive agent as a basein order to provide pressure-sensitive adhesiveness to the adherend.

The pressure-sensitive adhesive agent is a composition that contains apolymer showing a pressure-sensitive adhesiveness (pressure-sensitiveadhesive polymer) in the presence of an oil agent, other solvent, or thelike where the pressure-sensitive adhesive polymer exhibitspressure-sensitive adhesiveness by being dispersed or dissolved in theoil agent, other solvent, or the like. The type and composition of thepressure-sensitive adhesive polymer contained in the pressure-sensitiveadhesive agent are known in the art and, in the present invention, apressure-sensitive adhesive agent used in the pressure-sensitiveadhesive layer 3 of a conventional disposable pocket warmer can be used.Specific examples of the type of the pressure-sensitive adhesive agentinclude rubber-based pressure-sensitive adhesive agents, acrylicpressure-sensitive adhesive agents, silicone-based pressure-sensitiveadhesive agents, and urethane-based pressure-sensitive adhesive agents.

Specific examples of the pressure-sensitive adhesive polymer containedin the rubber-based pressure-sensitive adhesive agent includepolystyrene-polybutadiene-polystyrene copolymer,polystyrene-polyisoprene-polystyrene copolymer,polystyrene-polyethylene-polybutylene-polystyrene copolymer, andpolystyrene-polyethylene-polypropylene-polystyrene copolymer.

Specific examples of the silicone-based pressure-sensitive adhesiveagent include addition-reaction-curing type silicone-basedpressure-sensitive adhesive agents and peroxide-curing typesilicone-based pressure-sensitive adhesive agents.

Specific examples of the pressure-sensitive adhesive polymer containedin the acrylic pressure-sensitive adhesive agent include (meth)acrylicpolymers having an acrylic monomer as a constituent unit, such as methylacrylate, ethyl acrylate, 2-ethylhexyl acrylate, and butyl acrylate.

Specific examples of the pressure-sensitive adhesive polymer containedin the urethane-based pressure-sensitive adhesive agent include urethaneresins obtained by allowing a polyol such as polyether polyol, polyesterpolyol, polycarbonate polyol, or polycaprolactone polyol to react withpolyisocyanate such as diphenylmethane diisocyanate, tolylenediisocyanate, or hexamethylene diisocyanate.

These pressure-sensitive adhesive agents may be used either alone as onekind or as a combination of two or more kinds.

Among these pressure-sensitive adhesive agents, a rubber-basedpressure-sensitive adhesive agent is a preferable example.

The content of the pressure-sensitive adhesive agent in thepressure-sensitive adhesive layer 3 may be suitably set in accordancewith the pressure-sensitive adhesiveness to the adherend, the type ofthe pressure-sensitive adhesive agent, and the like, and may be, forexample, 60 to 99.9 wt %, preferably 70 to 99 wt %, and more preferably80 to 98 wt %.

In addition to the aforementioned components, the pressure-sensitiveadhesive layer 3 may contain a pharmacological component and a fragrancecomponent in accordance with the needs. Examples of such componentsinclude blood circulation promoters such as acidic mucopolysaccharide,matricaria recutita, buckeye, gingko, hamamelis extract, grapefruitextract, rosemary extract, lemon extract, vitamin E, and nicotinic acidderivatives; moisturizing agents such as glycerin, ceramide, collagen,hyaluronic acid, and squalane; fatigue relieving agents such as basilextract and juniper extract; pain relievers such as indometacin,diclofenac, flurbiprofen, ketoprofen, piroxicam, felbinac, methylsalicylate, and glycol salicylate sliming agents such as tea extract,ginseng extract, caffeine, buckeye, aminophylline, aescin,anthocyanidin, organic iodine compounds, hypericum erectum extract,filipendula extract, horsetail, rosemary, hedera helix, thiomucase, andhyaluronidase; swollenness alleviating agents such as terminalia, ammivisnaga, ammi majus, buckeye, anthocyanin, vitamin P, calendula,konkoritto acid, and silanol; peeling agents such as protease;depilatory agents such as calcium thioglycolate; and autonomic nerveregulating agents such as γ-oryzanol.

These pharmacological components and fragrance components may be usedeither alone as one kind or in combination of two or more kinds. Also,the content of the pharmacological components and fragrance componentsin the pressure-sensitive adhesive layer 3 may be suitably set inaccordance with the pharmacological effects or fragrance effects thatare to be imparted.

The application amount of the pressure-sensitive adhesive layer 3 may besuitably set in accordance with the adhesiveness to the adherend that isto be attached, the area for forming the pressure-sensitive adhesivelayer 3, and the like. The application amount of the pressure-sensitiveadhesive layer 3 in a region where the pressure-sensitive adhesive layer3 is formed on the first packaging material 21 may be, for example, 20to 150 g/m², preferably 40 to 120 g/m², and more preferably 60 to 100g/m².

The pressure-sensitive adhesive layer 3 may be provided over the wholesurface of the first packaging material 21 of the accommodation body 2or may be partially provided on the first packaging material 21 as longas the pressure-sensitive adhesive layer 3 is provided at least in aregion of the peripheral bonding section 24 of the first packagingmaterial 21 of the accommodation body 2.

A suitable example of the arrangement mode of the pressure-sensitiveadhesive layer 3 may be a mode such that the pressure-sensitive adhesivelayer 3 is provided on a whole surface or a part of the region of theaccommodation section 22 in the first packaging material 21 of theaccommodation body 2, and the pressure-sensitive adhesive layer 3 isprovided on the whole surface or a part of the region of the peripheralbonding section 24 in the first packaging material 21 of theaccommodation body 2. By providing the pressure-sensitive adhesive layer3 on a whole surface or a part of the region of the accommodationsection 22 in the first packaging material 21 in such a manner, the heatgenerator can be stably fixed onto the adherend at the time of use.Also, by providing the pressure-sensitive adhesive layer 3 on a wholesurface or a part of the region of the peripheral bonding section 24 inthe first packaging material 21, the adhesion between the release sheet4 and the pressure-sensitive adhesive layer 3 is improved duringstorage, and the volatile component can be furthermore stably maintainedwithin the pressure-sensitive adhesive layer 3.

When the pressure-sensitive adhesive layer 3 is provided in the regionof the accommodation section 22 in the first packaging material 21, thearea ratio of the part where the pressure-sensitive adhesive layer 3 isprovided (pressure-sensitive adhesive layer forming part) and the partwhere the pressure-sensitive adhesive layer 3 is not provided (nopressure-sensitive adhesive layer forming part) in the region may besuitably set in accordance with the adhesiveness to the adherend that isto be attached and the like, and may be typically, for example, 100:0 to2000, preferably 100:10 to 400, and more preferably 100:25 to 150, as anarea ratio of the pressure-sensitive adhesive layer forming part:nopressure-sensitive adhesive layer forming part.

Also, when the pressure-sensitive adhesive layer 3 is provided on thelower surface of the peripheral bonding section 24 in the firstpackaging material 21, the area ratio of the part where thepressure-sensitive adhesive layer 3 is provided (pressure-sensitiveadhesive layer forming part) and the part where the pressure-sensitiveadhesive layer 3 is not provided (no pressure-sensitive adhesive layerforming part) on the region may be suitably set in accordance with theadhesiveness to the adherend that is to be attached and the like, andmay be typically, for example, 100:0 to 2000, preferably 100:10 to 400,and more preferably 100:25 to 150, as an area ratio of thepressure-sensitive adhesive layer forming part:no pressure-sensitiveadhesive layer forming part.

When the pressure-sensitive adhesive layer 3 is provided partially tothe first packaging material 21, the shape of the formedpressure-sensitive adhesive layer 3 is not particularly limited, and maybe, for example, a stripe shape, a dot shape, a lattice shape, a netshape, a frame shape surrounding the ends of the first packagingmaterial 21, or the like.

The pressure-sensitive adhesive layer 3 is formed by application ontothe first packaging material 21 of the accommodation body 2 using aconventional coating method.

<Release Sheet>

In the heat generator of the present invention, the release sheet 4including the metal foil membrane 41 is let to adhere closely over thewhole surface of the pressure-sensitive adhesive layer 3 (the side thatis attached to the adherend) in a releasable state. By allowing therelease sheet 4 including the metal foil membrane 41 to adhere closelyto the pressure-sensitive adhesive layer 3 in this manner, it ispossible to prevent the volatile component contained in thepressure-sensitive adhesive layer 3 from being volatilized and scatteredinto the tight sealing bag during storage, and to maintain the volatilecomponent stably within the pressure-sensitive adhesive layer 3.

Specific examples, suitable examples, thickness, and the like of themetal foil membrane 41 used in the release sheet 4 are similar to thoseof the metal foil membrane used in the gas barrier layer 211 describedabove.

In the release sheet 4, one layer made of a single metal foil membranemay be provided, or alternatively, two or more of the same or differentmetal foil membranes may be provided.

A metal foil membrane, particularly an aluminum foil membrane, has anexcellent shape-following property, so that, in the heat generator ofthe present invention, the release sheet 4 can follow the stepdifference 2 a (height difference) that is formed at the boundarybetween the peripheral bonding section 24 and the accommodation section22 of the accommodation body 2, and can enhance the adhesion to thepressure-sensitive adhesive layer 3. This can prevent a gap from beinggenerated between the pressure-sensitive adhesive layer 3 and therelease sheet 4 in the region of the peripheral bonding section 24 andcan more effectively prevent the volatile component contained in thepressure-sensitive adhesive layer 3 from being volatilized into thetight sealing bag during storage. Here, when the release sheet 4 followsthe step difference 2 a that is formed at the boundary between theperipheral bonding section 24 and the accommodation section 22 of theaccommodation body 2, the release sheet 4 that is in close adhesion tothe pressure-sensitive adhesive layer 3 is in a state in which a stepdifference is formed in correspondence with the step difference 2 a.

Also, a substrate layer 42 may be included in the release sheet 4 inorder to support or enhance the strength of the metal foil membrane 41.The substrate layer 42 may be made, for example, of a resin film such aspolyethylene terephthalate, polyacrylonitrile, ethylene-vinyl alcoholcopolymer, or polypropylene; paper, or the like. Among the substratelayers 42, a resin film is preferable, and a polyethylene terephthalatefilm is more preferable. Also, these substrate layers 42 may be made ofa single layer alone or a multiple layer of two or more layers.

The thickness of the substrate layer 42 is not particularly limited, andmay be, for example, 1 to 100 μm, more preferably 3 to 50 μm.

When a laminated body of the metal foil membrane 41 and the substratelayer 42 is used as the release sheet 4, it is preferable that the metalfoil membrane 41 side is brought into contact with thepressure-sensitive adhesive layer 3 to achieve close adhesion; however,the substrate layer 42 side may be brought into contact with thepressure-sensitive adhesive layer 3 to achieve close adhesion as well.

Also, in the release sheet 4, the surface on the side that is broughtinto contact with the pressure-sensitive adhesive layer 3 may besubjected to a releasability imparting treatment such as siliconetreatment in accordance with the needs.

The oxygen permeability of the release sheet 4 is not particularlylimited as long as the release sheet 4 includes the metal foil membrane41; however, the oxygen permeability of the release sheet 4 may be, forexample, 0 to 0.5 cc/m²·day·atm, preferably 0 to 0.1 cc/m²·day·atm.

Also, the water vapor permeability of the release sheet 4 is notparticularly limited as long as the release sheet 4 includes the metalfoil membrane 41; however, the water vapor permeability of the releasesheet 4 may be, for example, 1.5 g/m²·day or less, preferably 0 to 1g/m²·day, more preferably 0 to 0.5 g/m²·day, and still more preferably 0to 0.1 g/m²·day.

Also, in a conventional heat generator, an auxiliary cutting line isoften carved by providing a penetrating section that penetrates in thethickness direction in the release sheet 4. However, in the heatgenerator of the present invention, it is preferable that the releasesheet 4 does not have a penetrating section that penetrates in thethickness direction. By not providing a penetrating section thatpenetrates in the thickness direction in the release sheet 4, thevolatile component contained in the pressure-sensitive adhesive layer 3can be more effectively prevented from being volatilized into the tightsealing bag during storage.

Also, in the heat generator of the present invention, the release sheet4 preferably has a concave-convex shape in the region of the peripheralbonding section 24 of the accommodation body 2 in a state of closeadhesion to the pressure-sensitive adhesive layer 3, and thepressure-sensitive adhesive layer 3 preferably has a concave-convexshape that follows the concave-convex shape of the release sheet 4. Inthis manner, because the pressure-sensitive adhesive layer 3 has aconcave-convex shape to follow the concave-convex shape of the releasesheet 4 in the region of the peripheral bonding section 24, the adhesionbetween the pressure-sensitive adhesive layer 3 and the release sheet 4is made more firm in the region of the peripheral bonding section 24,and the volatile component contained in the pressure-sensitive adhesivelayer 3 can be more effectively prevented from being volatilized intothe tight sealing bag during storage. Also, when a concave-convex shapeis formed in the region of the peripheral bonding section 24 of theaccommodation body 2, a concave-convex shape that follows theconcave-convex shape of the release sheet 4 may be formed also in thefirst packaging material 21 and the second packaging material 23 in theregion of the peripheral bonding section 24.

When a concave-convex shape is formed on the pressure-sensitive adhesivelayer 3 and the release sheet 4 in the region of the peripheral bondingsection 24 of the accommodation body 2, the height difference betweenthe concave part and the convex part of the concave-convex shape is notparticularly limited, and may be, for example, 1 to 3000 μm, preferably10 to 1000 μm.

Such a concave-convex shape can be formed by performing an embossingtreatment on the region of the peripheral bonding section 24 in a statein which the pressure-sensitive adhesive layer 3 and the release sheet 4are close adhesion to each other.

<Preferable Modes>

FIGS. 1 and 2 each show a schematic view of a cross-sectional structureof one preferable embodiment of the heat generator of the presentinvention. In the heat generators shown in FIGS. 1 and 2, theaccommodation section 22 and the peripheral bonding section 24 areformed by bonding the peripheral parts of the first packaging material21 and the second packaging material 23, and the accommodation body 2having a step difference 2 a at the boundary between the accommodationsection 22 and the peripheral bonding section 24 is formed. Aheat-generating composition that generates heat by being brought intocontact with oxygen is accommodated as a heat-generating section 1 inthe accommodation body 2. In the heat generator shown in FIG. 1, thefirst packaging material 21 of the accommodation body 2 is configuredfrom a lamination sheet in which a welded resin layer 212, a gas barrierlayer 211 made of a metal foil membrane, and a fiber substrate 213 arelaminated in this order in a direction from the accommodation section 22side towards the attachment surface. In the heat generator shown in FIG.2, the first packaging material 21 of the accommodation body 2 isconfigured from a lamination sheet in which a welded resin layer 212, afirst resin layer 214, a gas barrier layer 211 made of a vapordeposition film, and a fiber substrate 213 are laminated in this orderin a direction from the accommodation section 22 side towards theattachment surface. Also, in the heat generators shown in FIGS. 1 and 2,the second packaging material 23 of the accommodation body 2 is formedof a lamination sheet in which a gas-permeable resin layer 231 and afiber substrate 232 are laminated in this order in a direction from theaccommodation section 22 side towards the outside. In the heatgenerators shown in FIGS. 1 and 2, a pressure-sensitive adhesive layer 3is laminated on the first packaging material 21 of the accommodationbody 2, and the release sheet 4 is in close adhesion to thepressure-sensitive adhesive layer 3 by following the step difference 2a. Also, in the heat generators shown in FIGS. 1 and 2, the releasesheet 4 is formed of a lamination sheet in which the metal foil membrane41 and the substrate layer 42 are laminated in this order in a directionfrom the pressure-sensitive adhesive layer 3 side. Also, FIG. 3 shows anenlarged schematic view of the region E shown in FIG. 1. In FIG. 3, therelease sheet 4 is formed to have a concave-convex shape in theperipheral bonding section 24, and each of the layers constituting thepressure-sensitive adhesive layer 3, the first packaging material 21,and the second packaging material 23 is formed to have a concave-convexshape so as to follow the concave-convex shape of the release sheet 4.

<Mode of Use⋅Packaging Mode>

The heat generator of the present invention is used as a warming tool ora curing tool of a human body by attaching the pressure-sensitiveadhesive layer 3 to the adherend such as a skin or clothing. Inparticular, since the heat generator of the present invention canachieve an excellent warming function, the heat generator isparticularly suitably used as a curing tool for blood circulationpromotion, pain alleviation, stiff shoulder alleviation, or the like.

The adherend serving as an object of applying the heat generator of thepresent invention may be one that demands warming, and may be, forexample, a skin, a clothing, or the like. Among the adherends, a skin issuitable. When the heat generator of the present invention is used bybeing attached to a skin, the skin site serving as an object ofattachment is not particularly limited and may be, for example, an eye,a face, a neck, a shoulder, a waist, a back, a belly, a buttock, an arm,a leg, a foot bottom, or the like. Also, when the heat generator of thepresent invention is used by being attached to a clothing, the heatgenerator of the present invention may be attached to a site of theclothing corresponding to the site of the human body to which it iswished to impart warming. Also, the type of the clothing serving as anobject of applying the heat generator of the present invention is notparticularly limited, however, the type of the clothing is preferably anunderwear in view of efficiently imparting warming to the human body.

When the heat-generating section 1 is a heat-generating composition thatgenerates heat by being brought into contact with oxygen, the heatgenerator of the present invention is accommodated in a tight sealingbag having an oxygen barrier property, so as to provide theheat-generating composition in a state that is not contact with air. Byopening the tight sealing bag at the time of use, the heat-generatingcomposition is brought into contact with air, and the heat generationstarts.

EXAMPLES

The present invention will be more specifically described by showingExamples; however, the present invention is not limited to these.

Test Example 1 1. Production of Heat Generator

First packaging materials A to D (rectangles with a longitudinal sidebeing 13 cm and a lateral side being 9.5 cm) each made of anon-gas-permeable lamination sheet having a layer configuration shown inTable 1 were prepared. Also, for each of the first packaging materials,the oxygen permeability was measured under conditions with a temperatureof 20° C. and a humidity of 90% RH in accordance with the differentialpressure method defined in JIS K 7126-1:2006. Further, for each of thefirst packaging materials, the water vapor permeability was measuredunder conditions with a temperature of 40° C. and a humidity of 90% RHin accordance with the cup method defined in JIS Z0208:1976.

TABLE 1 Oxygen Water vapor permeability permeability Layer structure(cc/m² · day) (g/m² · day) First Lamination sheet in which apolyethylene film (having a thickness of 30 μm), 0.1 0.1 packaging analuminum foil membrane (having a thickness of 9 μm), and a material Anonwoven cloth (made of polyethylene terephthalate, weight per unit areaof 30 g/m²) are laminated in this order. Bonding between thepolyethylene film and the aluminum foil membrane and between thealuminum foil membrane and the nonwoven cloth was carried out by drylamination First Lamination sheet in which a polyethylene film (having athickness of 30 μm), 1.5 1.5 packaging a polyethylene terephthalatelayer (having a thickness of 12 μm), a material B vapor deposition filmmade of aluminum oxide (having a thickness of 500 Å), and a nonwovencloth (made of polyethylene terephthalate, weight per unit area of 30g/m²) are laminated in this order. Bonding between the polyethylene filmand the polyethylene terephthalate layer and between the vapordeposition film and the nonwoven cloth was carried out by drylamination. The vapor deposition film was formed by vapor deposition ofaluminum oxide onto the polyethylene terephthalate layer. FirstLamination sheet in which a polyethylene film (having a thickness of 30μm), 0.5 0.5 packaging a polyethylene terephthalate layer (having athickness of 12 μm), a material C vapor deposition film made of silica(having a thickness of 500 Å), and a nonwoven cloth (made ofpolyethylene terephthalate, weight per unit area of 30 g/m²) arelaminated in this order. Bonding between the polyethylene film and thepolyethylene terephthalate layer and between the vapor deposition filmand the nonwoven cloth was carried out by dry lamination. The vapordeposition film was formed by vapor deposition of silica onto thepolyethylene terephthalate layer. First Lamination sheet in which apolyethylene film (having a thickness of 30 μm), 25.2 15.7 packaging apolyethylene terephthalate layer (having a thickness of 12 μm), andmaterial D a nonwoven cloth (made of polyethylene terephthalate, weightper unit area of 30 g/m²) are laminated in this order. Bonding betweenthe polyethylene film and the polyethylene terephthalate layer andbetween the polyethylene terephthalate layer and the nonwoven cloth wascarried out by dry lamination.

A pressure-sensitive adhesive layer forming composition 1 containing thefollowing components that were mixed by heating at 140° C. was appliedonto the whole surface of the nonwoven cloth of the first packagingmaterial so as to attain an application amount of 100 g/m², followed bycooling to form a pressure-sensitive adhesive layer on the firstpackaging material.

<Pressure-Sensitive Adhesive Layer Forming Composition 1>

Menthol (trade name: “HAKKANO”, manufactured by Nagaoka & Co., Ltd.): 5wt %

Rubber-based pressure-sensitive adhesive agent: 95 wt %

Total: 100 wt %

Release sheets (rectangles with a longitudinal side being 13 cm and alateral side being 9.5 cm) each having a layer configuration shown inTable 2 were prepared. The oxygen permeability and the water vaporpermeability of the release sheets were measured by methods similar tothose described above. Subsequently, each release sheet was bonded tothe pressure-sensitive adhesive layer on the first packaging material.During this, the release sheets A to C were placed so that the aluminumfoil membrane side of the release sheet A, the vapor deposition filmside of the release sheet B, and the surface of the release sheet Csubjected to a silicone treatment would be in surface contact with therespective pressure-sensitive adhesive layers.

TABLE 2 Oxygen Water vapor permeability permeability Layer structure(cc/m² · day) (g/m² · day) Release Lamination sheet in which an aluminumfoil membrane (having a 0.1 0.1 sheet A thickness of 9 μm) and apolyethylene terephthalate layer (having a thickness of 12 μm) arelaminated in this order. Bonding between the aluminum foil membrane andthe polyethylene terephthalate layer was carried out by dry laminationRelease Lamination sheet in which a vapor deposition film made ofaluminum 1.5 1.5 sheet B oxide (having a thickness of 500 Å) and apolyethylene terephthalate layer (having a thickness of 12 μm) arelaminated in this order. The vapor deposition film was formed by vapordeposition of aluminum oxide onto the polyethylene terephthalate layer.Release Polyethylene terephthalate film subjected to a siliconetreatment (having 25.2 15.7 sheet C a thickness of 12 μm).

Also, a second packaging material (rectangle with a longitudinal sidebeing 13 cm and a lateral side being 9.5 cm) made of a gas-permeablelamination sheet in which a polyethylene film (having a thickness of 70μm) provided with pores and a nonwoven cloth (made of polyethyleneterephthalate, weight per unit area of 30 g/m²) had been bonded by drylamination was separately prepared.

Subsequently, 22 g of iron powder, 6 g of activated carbon, and 10 g ofa mixture of water-soluble salt, water retention agent, and water(mixture of sodium chloride, water-absorbing resin, vermiculite, water,and the like; containing 8.5 g of water) were mixed to prepare aheat-generating composition. The peripheral parts of the first packagingmaterial and the second packaging material were thermally welded witheach other in a state in which 38 g of the obtained heat-generatingcomposition had been interposed between the polyethylene film side ofthe first packaging material and the polyethylene film side of thesecond packaging material, and the heat-generating composition wasaccommodated in the formed accommodation section (with a longitudinalside being 12 cm and a lateral side being 8.5 cm). Subsequently, theperipheral bonding section where the first packaging material and thesecond packaging material had been welded was subjected to an embossingtreatment using an embossing template with an undulation depth of 200 μmfrom the release sheet side to form a concave-convex shape from thesurface of the release sheet down to the depth reaching thepressure-sensitive adhesive layer, thereby to form a heat generator. Theproduced heat generator was quickly accommodated into anon-gas-permeable sealing bag and tightly sealed. Here, in the producedheat generator, combinations of the first packaging material and thesecond packaging material shown in Table 3 were adopted.

In the obtained heat generators of Examples 1 to 3, it was found outthat the release sheet sufficiently followed the step differencegenerated at the boundary between the peripheral bonding section and theaccommodation section of the accommodation body, and the adhesionbetween the pressure-sensitive adhesive layer and the release sheet hadbeen enhanced in the peripheral bonding section region.

2. Evaluation of Retained Amount of Menthol in Pressure-SensitiveAdhesive Layer by Storage

The heat generator accommodated in the tight sealing bag was stored at50° C. for two months. The pressure-sensitive adhesive layer of the heatgenerators immediately after production and after storage for two monthswas peeled off, and this was added into chloroform and subjected to asupersonic wave treatment for 30 minutes to extract menthol.Subsequently, the amount of extracted menthol was measured by gaschromatography so as to determine the amount of menthol in thepressure-sensitive adhesive layer. Also, the retention rate of mentholin the pressure-sensitive adhesive layer was calculated in accordancewith the following calculation formula.

Retention rate (%) of menthol in pressure-sensitive adhesivelayer={(amount of menthol in pressure-sensitive adhesive layer afterstorage for two months)/(amount of menthol in pressure-sensitiveadhesive layer immediately after production)}×100  [Numerical formula 1]

The obtained results are shown in Table 3. The amount of menthol in thepressure-sensitive adhesive layer greatly decreased after storage fortwo months in the case in which the metal foil membrane had not beenprovided in the release sheet even though a metal foil membrane or avapor deposition film had been provided in the first packaging material(Comparative Examples 1 and 2). In contrast, menthol was stablymaintained in the pressure-sensitive adhesive layer even after storagefor two months when a metal foil membrane had been provided in therelease sheet (Examples 1 to 3).

TABLE 3 Amount of Amount of menthol in menthol in pressure- Retentionrate of pressure- sensitive menthol in sensitive adhesive layerpressure- First packaging material adhesive layer after storage forsensitive Gas barrier layer Release sheet immediately after two monthsadhesive layer Type put to use Type Layer material production (wt %) (wt%) (%) Example 1 A Metal foil membrane A Metal foil membrane 3.9 3.692.3 Example 2 B Vapor deposition A Metal foil membrane 3.9 3.2 82.1film Example 3 C Vapor deposition A Metal foil membrane 3.9 3.1 79.5film Comparative B Vapor deposition C PET 3.9 0.7 17.9 Example 1 filmComparative A Metal foil membrane C PET 3.9 0.9 23.1 Example 23. Evaluation of Heat Generation Characteristics of Heat Generator afterStorage

The heat generators immediately after production (Example 1 andComparative Example 1) were each put into a tight sealing bag and storedat 50° C. for two months. Thereafter, the heat generationcharacteristics were evaluated. Specifically, 10 pieces of heatgenerators were each taken out from the tight sealing bag, and the heatgeneration temperature was measured with lapse of time from the timepoint at which the heat generators were taken out from the tight sealingbag in accordance with the method defined in JIS S 4100:2007.

The obtained results are shown in FIG. 4. As a result of this, it wasfound out that, in the heat generators of Comparative Example 1, theheat generation temperature decreased during the period from the time of120 minutes to the time of 600 minutes after the heat generator wastaken out from the tight sealing bag, and further, variation in the heatgeneration temperature among the 10 pieces of heat generators was large.Also, in some of the heat generators of Comparative Example 1, thetemperature rose after the temperature once lowered, thereby failing toshow a stable heat generation behavior. In contrast, in the heatgenerators of Example 1, heat was generated stably at a temperature of40° C. or higher during the period from the time of 20 minutes to thetime of 780 minutes after the heat generator was taken out from thetight sealing bag, and also variation in the heat generation temperatureamong the 10 pieces of heat generators was small. In the heat generatorsof Example 1, it seems that menthol was stably maintained in thepressure-sensitive adhesive layer during storage, so that menthol wasprevented from adhering to the heat-generating composition. As a resultof this, a stable heat generation temperature was realized, and the heatgeneration temperature was uniform among the 10 pieces of heatgenerators.

Test Example 2 1. Production of Heat Generator Example 4

A heat generator was produced under the same conditions as in theaforementioned Example 1 except that the pressure-sensitive adhesivelayer forming composition 2 containing the following components wasused.

<Pressure-Sensitive Adhesive Layer Forming Composition 2>

Menthol (trade name: “HAKKANO”, manufactured by Nagaoka & Co., Ltd.): 5wt %

Camphor (trade name: “dl-camphor [SP]”, manufactured by Nagaoka & Co.,Ltd.): 1.5 wt %

Ginger extract (trade name: “Ginger Extract Liquid”, manufactured byAlps Pharmaceutical Industry Co., Ltd.) (liquid form) (corresponding toabout 0.12 wt % as converted in terms of dry raw material): 3 wt %

Rubber-based pressure-sensitive adhesive agent: 90.5 wt %

Total: 100 wt %

Comparative Example 3

A heat generator was produced under the same conditions as in theaforementioned Example 4 except that the first packaging material D andthe release sheet C were used.

2. Evaluation of Sensation of Hotness and Sensation of Coldness

The heat generators immediately after production (Example 4 andComparative Example 3) were each put into a tight sealing bag and storedat 50° C. for two months. Thereafter, the sensation of hotness and thesensation of coldness were evaluated by 10 subject persons being tested.Specifically, after the subject person being tested maintained for 10minutes a posture in which the forearm was placed on a desk having thesame height as the heart in a sitting position, the heat generator takenout from the tight sealing bag was directly attached to the forearm onthe desk. Thereafter, the sensation of hotness and the sensation ofcoldness that are exhibited every 5 minutes during the time of 50minutes were scored in accordance with the following determinationstandard, and an average value thereof was calculated.

(Determination Standard of Sensation of Hotness and Sensation ofColdness)

5: Extremely strongly perceived4: Strongly perceived

3: Perceived

2: A little weakly perceived1: Not perceived at all

The obtained results are shown in FIG. 5. As a result of this, it hasbeen made clear that, in the heat generator of Example 4, the sensationof hotness perceived from the time of the start of use was perceivedearly, and further, the sensation of hotness was strongly perceived ascompared with the heat generator of Comparative Example 3. In the heatgenerator of Example 4, the first packaging material has a metal foilmembrane, and it seems that an early onset of the sensation of hotnessand a stronger sensation of hotness were realized by improvement in thethermal conductivity and generation of radiation heat brought about bythe metal foil membrane. Also, in the heat generator of Example 4, thesensation of coldness was sufficiently perceived as compared with theheat generator of Comparative Example 3.

DESCRIPTION OF REFERENCE SIGNS

-   -   1: Heat-generating section    -   2: Accommodation body    -   2 a: Step difference (height difference)    -   21: First packaging material    -   211: Gas barrier layer    -   212: Welded resin layer    -   213: Fiber substrate    -   214: First resin layer    -   22: Accommodation section    -   23: Second packaging material    -   231: Gas-permeable resin layer    -   232: Fiber substrate    -   24: Peripheral bonding section    -   3: Pressure-sensitive adhesive layer    -   4: Release sheet    -   41: Metal foil membrane    -   42: Substrate layer

1. A heat generator that is used by being attached to an adherend, theheat generator comprising: a heat-generating section for generating heatthat is transmitted to the adherend; an accommodation body foraccommodating the heat-generating section, the accommodation body havingan attachment surface that is attached to the adherend; apressure-sensitive adhesive layer provided to an attachment surface sideof the accommodation body; and a release sheet provided to an attachmentsurface side of the pressure-sensitive adhesive layer and beingreleasable from the pressure-sensitive adhesive layer, wherein theaccommodation body is composed of a first packaging material disposed onan attachment surface side and a second packaging material disposed on asurface opposite to the attachment surface, the accommodation bodyincludes a peripheral bonding section where peripheral parts of thefirst packaging material and the second packaging material are bonded,and an accommodation section that forms a space for accommodating theheat-generating section, the pressure-sensitive adhesive layer isprovided at least in a region where the peripheral bonding section ofthe first packaging material is formed, and the release sheet includes ametal foil membrane.
 2. The heat generator according to claim 1, whereinthe release sheet is in close adhesion to the pressure-sensitiveadhesive layer by following a step difference that is generated at aboundary between the peripheral bonding section and the space part ofthe accommodation body.
 3. The heat generator according to claim 1 or 2,wherein the release sheet has a concave-convex shape in a region wherethe peripheral bonding section of the first packaging material isformed, and the pressure-sensitive adhesive layer has a concave-convexshape that follows the concave-convex shape of the release sheet.
 4. Theheat generator according to claim 3, wherein the concave-convex shapesof the release sheet and the pressure-sensitive adhesive layer areformed by an embossing treatment.
 5. The heat generator according to anyone of claims 1 to 4, wherein the first packaging material has an oxygenpermeability of 1.5 cc/m²·day·atm or less.
 6. The heat generatoraccording to any one of claims 1 to 5, wherein the metal foil membraneis an aluminum foil membrane or a stainless steel foil membrane.
 7. Theheat generator according to any one of claims 1 to 6, wherein thevolatile component is at least one kind selected from the groupconsisting of menthol, camphor, thymol, spilanthol, mint oil, peppermintoil, methyl salicylate, capsaicin, vanillyl nonylic acid amide, sage,caffeine, tocopherol nicotinate, benzyl nicotinate, vanillyl butylether, vanillyl ethyl ether, gingerol, vanillyl propyl ether, vanillylpentyl ether, vanillyl hexyl ether, vanillyl butyl ether acetate, hotpepper extract, and ginger extract.
 8. The heat generator according toany one of claims 1 to 7, wherein the release sheet does not have apenetrating section that penetrates in a thickness direction.